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Li J, Docile HJ, Fisher D, Pronyuk K, Zhao L. Current Status of Malaria Control and Elimination in Africa: Epidemiology, Diagnosis, Treatment, Progress and Challenges. J Epidemiol Glob Health 2024; 14:561-579. [PMID: 38656731 PMCID: PMC11442732 DOI: 10.1007/s44197-024-00228-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Accepted: 04/10/2024] [Indexed: 04/26/2024] Open
Abstract
The African continent carries the greatest malaria burden in the world. Falciparum malaria especially has long been the leading cause of death in Africa. Climate, economic factors, geographical location, human intervention and unstable security are factors influencing malaria transmission. Due to repeated infections and early interventions, the proportion of clinically atypical malaria or asymptomatic plasmodium carriers has increased significantly, which easily lead to misdiagnosis and missed diagnosis. African countries have made certain progress in malaria control and elimination, including rapid diagnosis of malaria, promotion of mosquito nets and insecticides, intermittent prophylactic treatment in high-risk groups, artemisinin based combination therapies, and the development of vaccines. Between 2000 and 2022, there has been a 40% decrease in malaria incidence and a 60% reduction in mortality rate in the WHO African Region. However, many challenges are emerging in the fight against malaria in Africa, such as climate change, poverty, substandard health services and coverage, increased outdoor transmission and the emergence of new vectors, and the growing threat of resistance to antimalarial drugs and insecticides. Joint prevention and treatment, identifying molecular determinants of resistance, new drug development, expanding seasonal malaria chemo-prevention intervention population, and promoting the vaccination of RTS, S/AS01 and R21/Matrix-M may help to solve the dilemma. China's experience in eliminating malaria is conducive to Africa's malaria prevention and control, and China-Africa cooperation needs to be constantly deepened and advanced. Our review aims to help the global public develop a comprehensive understanding of malaria in Africa, thereby contributing to malaria control and elimination.
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Affiliation(s)
- Jiahuan Li
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Haragakiza Jean Docile
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - David Fisher
- Department of Medical Biosciences, Faculty of Natural Sciences, University of The Western Cape, Cape Town, South Africa
| | - Khrystyna Pronyuk
- Department of Infectious Diseases, O. Bogomolets National Medical University, Kyiv, Ukraine
| | - Lei Zhao
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
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Hoyt J, Okello G, Bange T, Kariuki S, Jalloh MF, Webster J, Hill J. RTS,S/AS01 malaria vaccine pilot implementation in western Kenya: a qualitative longitudinal study to understand immunisation barriers and optimise uptake. BMC Public Health 2023; 23:2283. [PMID: 37980467 PMCID: PMC10657022 DOI: 10.1186/s12889-023-17194-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 11/09/2023] [Indexed: 11/20/2023] Open
Abstract
BACKGROUND Malaria is a significant public health threat in sub-Saharan Africa, particularly among children. The RTS,S/AS01 malaria vaccine reduces the risk and severity of malaria in children. RTS,S/AS01 was piloted in three African countries, Ghana, Kenya and Malawi, to assess safety, feasibility and cost-effectiveness in real-world settings. A qualitative longitudinal study was conducted as part of the feasibility assessment. This analysis explores RTS,S/AS01 vaccination barriers and identifies potential motivators among caregivers in three sub-counties in western Kenya. METHODS A cohort of 63 caregivers with a malaria vaccine eligible child was interviewed at three time points over 24 months. A sub-set of 11 caregivers whose eligible children were either partially or non-vaccinated were selected for this sub-analysis. The 5A Taxonomy for root causes of under-vaccination was used to organise the inductively-coded data into categories (awareness, acceptance, access, affordability, and activation) and identify the factors influencing uptake across caregivers. A trajectory analysis was conducted to understand changes in factors over time within each caregiver experience. Caregiver narratives are used to illustrate how the factors influencing uptake were interrelated and changed over time. RESULTS Lack of awareness, previous negative experiences with routine childhood immunisations and the burden of getting to the health facility contributed to caregivers initially delaying uptake of the vaccine. Over time concerns about vaccine side effects diminished and anticipated vaccination benefits strongly motivated caregivers to vaccinate their children. Persistent health system barriers (e.g., healthcare provider strikes, vaccine stockouts, negative provider attitudes) meant some children missed the first-dose eligibility window by aging-out. CONCLUSIONS Caregivers in this study believed the RTS,S/AS01 to be effective and were motivated to have their children vaccinated. Despite these positive perceptions of the malaria vaccine, uptake was substantially hindered by persistent health system constraints. Negative provider attitudes emerged as a powerful deterrent to attending immunisation services and hampered uptake of the vaccine. Strategies that focus on improving interpersonal communication skills among healthcare providers are needed.
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Affiliation(s)
- Jenna Hoyt
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK.
| | - George Okello
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
- Kenya Medical Research Institute/Centre for Global Health Research, Kisumu, Kenya
| | - Teresa Bange
- Kenya Medical Research Institute/Centre for Global Health Research, Kisumu, Kenya
| | - Simon Kariuki
- Kenya Medical Research Institute/Centre for Global Health Research, Kisumu, Kenya
| | - Mohamed F Jalloh
- Global Immunization Division, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Jayne Webster
- Disease Control Department, London School of Tropical Medicine and Hygiene, London, UK
| | - Jenny Hill
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
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Orondo PW, Zhou G, Ochwedo KO, Wang X, Ondeto BM, Lee MC, Nyanjom SG, Atieli H, Githeko AK, Kazura JW, Yan G. Effect of predators on Anopheles arabiensis and Anopheles funestus larval survivorship in Homa Bay County Western Kenya. Malar J 2023; 22:298. [PMID: 37798779 PMCID: PMC10557226 DOI: 10.1186/s12936-023-04741-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 10/03/2023] [Indexed: 10/07/2023] Open
Abstract
BACKGROUND The rise of insecticide resistance against malaria vectors in sub-Saharan Africa has resulted in the need to consider other methods of vector control. The potential use of biological methods, including larvivorous fish, Bacillus thuringiensis israelensis (Bti) and plant shading, is sustainable and environmentally friendly options. This study examined the survivorship of Anopheles arabiensis and Anopheles funestus larvae and habitat productivity in four permanent habitat types in Homa Bay county, western Kenya. METHODS Predator densities were studied in a laboratory setup while habitat productivity and larval survivorship was studied in field setup. RESULTS Fish were observed as the most efficient predator (75.8% larval reduction rate) followed by water boatman (69%), and dragonfly nymph (69.5%) in predation rates. Lower predation rates were observed in backswimmers (31%), water beetles (14.9%), water spiders (12.2%), mayflies (7.3%), and tadpoles (6.9%). Increase in predator density in the field setup resulted in decreased Culex larval density. Larval and pupa age-specific distribution was determined and their survivorship curves constructed. Combined larvae (Stage I-IV) to pupa mortality was over 97% for An. arabiensis and 100% for An. funestus. The highest larval stage survival rate was from larval stages I to II and the lowest from larval stage IV to pupa. Stage-specific life tables indicated high mortality rates at every developmental stage, especially at the larval stage II and III. CONCLUSION Determination of the efficiency of various larval predators and habitat productivity will help with the correct identification of productive habitats and selection of complementary vector control methods through environmental management and/or predator introduction (for instance fish) in the habitats.
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Affiliation(s)
- Pauline Winnie Orondo
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya.
| | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Kevin O Ochwedo
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Xiaoming Wang
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Benyl M Ondeto
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Steven G Nyanjom
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Harrysone Atieli
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Andrew K Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - James W Kazura
- Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA.
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4
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Ohene-Adjei K, Asante KP, Akuffo KO, Tounaikok N, Asiamah M, Owiredu D, Manu AA, Danso-Appiah A. Malaria vaccine-related adverse events among children under 5 in sub-Saharan Africa: systematic review and meta-analysis protocol. BMJ Open 2023; 13:e076985. [PMID: 37793915 PMCID: PMC10551995 DOI: 10.1136/bmjopen-2023-076985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 09/11/2023] [Indexed: 10/06/2023] Open
Abstract
INTRODUCTION The RTS,S vaccine has been approved for use in children under 5 living in moderate to high malaria transmission areas. However, clinically important adverse events have been reported in countries in sub-Saharan Africa. This systematic review aims to assess the frequency, severity and clinical importance of vaccine-related adverse events. METHODS AND ANALYSIS This systematic review protocol has been prepared following robust methods and reported in line with the Preferred Reporting Items for Systematic reviews and Meta-Analyses for protocols guidelines. We will search PubMed, CINAHL, LILACS, Google Scholar, SCOPUS, WEB OF SCIENCE, Cochrane library, HINARI, African Journals Online, Trip Pro and TOXNET from 2000 to 30 September 2023, without language restrictions. We will also search conference proceedings, dissertations, World Bank Open Knowledge Repository, and WHO, PATH, UNICEF, Food and Drugs Authorities and European Medicines Agency databases, preprint repositories and reference lists of relevant studies for additional studies. Experts in the field will be contacted for unpublished or published studies missed by our searches. At least two reviewers will independently select studies and extract data using pretested tools and assess risk of bias in the included studies using the Cochrane risk of bias tool. Any disagreements will be resolved through discussion between the reviewers. Heterogeneity will be explored graphically, and statistically using the I2 statistic. We will conduct random-effects meta-analysis when heterogeneity is appreciable, and express dichotomous outcomes (serious adverse events, cerebral malaria and febrile convulsion) as risk ratio (RR) with their 95% CI. We will perform subgroup analysis to assess the impact of heterogeneity and sensitivity analyses to test the robustness of the effect estimates. The overall level of evidence will be assessed using Grading of Recommendations Assessment, Development and Evaluation. ETHICS AND DISSEMINATION Ethical approval is not required for a systematic review. The findings of this study will be disseminated through stakeholder forums, conferences and peer-review publications. PROSPERO REGISTRATION NUMBER CRD42021275155.
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Affiliation(s)
- Kennedy Ohene-Adjei
- Department of Epidemiology and Disease Control, School of Public Health, College of Health Sciences, University of Ghana, Accra, Ghana
- Tain District Health Directorate, Ghana Health Service, Tain, Ghana
| | - Kwaku Poku Asante
- Research and Development Division, Kintampo Health Research Centre, Ghana Health Service, Kintampo, Kintampo North Municipality, Bono East Region, Ghana
| | - Kwadwo Owusu Akuffo
- Department of Optometry and Visual Science, College of Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Narcisse Tounaikok
- Centre for Evidence Synthesis and Policy, School of Public Health, University of Ghana, Accra, Ghana
- Department of Human and Animal Health, University of Emi Koussi, N'Djamena, Chad
| | - Morrison Asiamah
- Department of Electron Microscopy and Histopathology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - David Owiredu
- Department of Epidemiology and Disease Control, School of Public Health, College of Health Sciences, University of Ghana, Accra, Ghana
- Centre for Evidence Synthesis and Policy, School of Public Health, University of Ghana, Accra, Ghana
| | - Alexander Ansah Manu
- Department of Epidemiology and Disease Control, School of Public Health, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Anthony Danso-Appiah
- Department of Epidemiology and Disease Control, School of Public Health, College of Health Sciences, University of Ghana, Accra, Ghana
- Centre for Evidence Synthesis and Policy, School of Public Health, University of Ghana, Accra, Ghana
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Mak J, Sriudomporn S, Moss WJ, Patenaude BN. An Estimate Of The Return On Investment Of A Malaria Vaccine In 20 Sub-Saharan African Countries, 2021-30. Health Aff (Millwood) 2023; 42:1091-1099. [PMID: 37549331 DOI: 10.1377/hlthaff.2022.01328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Abstract
Malaria is a leading global health problem that was responsible for an estimated 619,000 deaths worldwide in 2021. We modeled the return on investment (ROI) for the introduction and continuation of a four-dose malaria vaccine, RTS,S/AS01, from 2021 to 2030 in twenty sub-Saharan African countries supported by Gavi, the Vaccine Alliance. We used the Decade of Vaccine Economics benefits and costing outputs to calculate an ROI using health impact data modeled by the Swiss Tropical and Public Health Institute (hereafter "Swiss") and Imperial College London (hereafter "Imperial"). The Swiss estimates with a base vaccine price of US$7.00 resulted in an ROI of 0.42, and the Imperial impact estimates with the same base vaccine price resulted in an ROI of 2.30. Inclusion of the fifth seasonal dose for ten countries exhibiting high seasonal disease burden increased the Swiss ROI by 143 percent, to 1.02, and the Imperial ROI by 23.5 percent, to 2.84. To improve ROI, decision makers should continue to improve delivery platforms, decrease vaccine delivery costs, deliver the malaria vaccine in fewer doses, and provide access to vaccine resources.
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Affiliation(s)
- Joshua Mak
- Joshua Mak , Johns Hopkins University, Baltimore, Maryland
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6
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Tukwasibwe S, Mboowa G, Sserwadda I, Nankabirwa JI, Arinaitwe E, Ssewanyana I, Taremwa Y, Tumusiime G, Kamya MR, Jagannathan P, Nakimuli A. Impact of high human genetic diversity in Africa on immunogenicity and efficacy of RTS,S/AS01 vaccine. Immunogenetics 2023; 75:207-214. [PMID: 37084013 PMCID: PMC10119520 DOI: 10.1007/s00251-023-01306-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 04/06/2023] [Indexed: 04/22/2023]
Abstract
In modern medicine, vaccination is one of the most effective public health strategies to prevent infectious diseases. Indisputably, vaccines have saved millions of lives by reducing the burden of many serious infections such as polio, tuberculosis, measles, pneumonia, and tetanus. Despite the recent recommendation by the World Health Organization (WHO) to roll out RTS,S/AS01, this malaria vaccine still faces major challenges of variability in its efficacy partly due to high genetic variation in humans and malaria parasites. Immune responses to malaria vary between individuals and populations. Human genetic variation in immune system genes is the probable cause for this heterogeneity. In this review, we will focus on human genetic factors that determine variable responses to vaccination and how variation in immune system genes affect the immunogenicity and efficacy of the RTS,S/AS01 vaccine.
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Affiliation(s)
- Stephen Tukwasibwe
- Infectious Diseases Research Collaboration, Kampala, Uganda.
- Infectious Diseases Institute, College of Health Sciences, Makerere University, Kampala, Uganda.
- School of Medicine, Uganda Christian University, Kampala, Uganda.
| | - Gerald Mboowa
- Infectious Diseases Institute, College of Health Sciences, Makerere University, Kampala, Uganda
| | - Ivan Sserwadda
- Infectious Diseases Institute, College of Health Sciences, Makerere University, Kampala, Uganda
| | | | | | | | - Yoweri Taremwa
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Gerald Tumusiime
- School of Medicine, Uganda Christian University, Kampala, Uganda
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
- School of Medicine, College of Health Sciences, Makerere University, Kampala, Uganda
| | | | - Annettee Nakimuli
- School of Medicine, College of Health Sciences, Makerere University, Kampala, Uganda
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7
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Topazian HM, Schmit N, Gerard-Ursin I, Charles GD, Thompson H, Ghani AC, Winskill P. Modelling the relative cost-effectiveness of the RTS,S/AS01 malaria vaccine compared to investment in vector control or chemoprophylaxis. Vaccine 2023; 41:3215-3223. [PMID: 37080831 DOI: 10.1016/j.vaccine.2023.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 04/03/2023] [Accepted: 04/03/2023] [Indexed: 04/22/2023]
Abstract
BACKGROUND The World Health Organization has recommended a 4-dose schedule of the RTS,S/AS01 (RTS,S) vaccine for children in regions of moderate to high P. falciparum transmission. Faced with limited supply and finite resources, global funders and domestic malaria control programs will need to examine the relative cost-effectiveness of RTS,S and identify target areas for vaccine implementation relative to scale-up of existing interventions. METHODS Using an individual-based mathematical model of P. falciparum, we modelled the cost-effectiveness of RTS,S across a range of settings in sub-Saharan Africa, incorporating various rainfall patterns, insecticide-treated net (ITN) use, treatment coverage, and parasite prevalence bands. We compare age-based and seasonal RTS,S administration to increasing ITN usage, switching to next generation ITNs in settings experiencing insecticide-resistance, and introduction of seasonal malaria chemoprevention (SMC) in areas of seasonal transmission. RESULTS For RTS,S to be the most cost-effective intervention option considered, the maximum cost per dose was less than $9.30 USD in 90.9% of scenarios. Nearly all (89.8%) values at or above $9.30 USD per dose were in settings with 60% established bed net use and / or with established SMC, and 76.3% were in the highest PfPR2-10 band modelled (40%). Addition of RTS,S to strategies involving 60% ITN use, increased ITN usage or a switch to PBO nets, and SMC, if eligible, still led to significant marginal case reductions, with a median of 2,653 (IQR: 1,741 to 3,966) cases averted per 100,000 people annually, and 82,270 (IQR: 54,034 to 123,105) cases averted per 100,000 fully vaccinated children (receiving at least three doses). CONCLUSIONS Use of RTS,S results in reductions in malaria cases and deaths even when layered upon existing interventions. When comparing relative cost-effectiveness, scale up of ITNs, introduction of SMC, and switching to new technology nets should be prioritized in eligible settings.
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Affiliation(s)
- Hillary M Topazian
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK.
| | - Nora Schmit
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Ines Gerard-Ursin
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Giovanni D Charles
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Hayley Thompson
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Peter Winskill
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
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Ivanochko D, Fabra-García A, Teelen K, van de Vegte-Bolmer M, van Gemert GJ, Newton J, Semesi A, de Bruijni M, Bolscher J, Ramjith J, Szabat M, Vogt S, Kraft L, Duncan S, Lee SM, Kamya MR, Feeney ME, Jagannathan P, Greenhouse B, Sauerwein RW, Richter King C, MacGill RS, Bousema T, Jore MM, Julien JP. Potent transmission-blocking monoclonal antibodies from naturally exposed individuals target a conserved epitope on Plasmodium falciparum Pfs230. Immunity 2023; 56:420-432.e7. [PMID: 36792575 PMCID: PMC9942874 DOI: 10.1016/j.immuni.2023.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/04/2022] [Accepted: 01/12/2023] [Indexed: 02/16/2023]
Abstract
Pfs230 is essential for Plasmodium falciparum transmission to mosquitoes and is the protein targeted by the most advanced malaria-transmission-blocking vaccine candidate. Prior understanding of functional epitopes on Pfs230 is based on two monoclonal antibodies (mAbs) with moderate transmission-reducing activity (TRA), elicited from subunit immunization. Here, we screened the B cell repertoire of two naturally exposed individuals possessing serum TRA and identified five potent mAbs from sixteen Pfs230 domain-1-specific mAbs. Structures of three potent and three low-activity antibodies bound to Pfs230 domain 1 revealed four distinct epitopes. Highly potent mAbs from natural infection recognized a common conformational epitope that is highly conserved across P. falciparum field isolates, while antibodies with negligible TRA derived from natural infection or immunization recognized three distinct sites. Our study provides molecular blueprints describing P. falciparum TRA, informed by contrasting potent and non-functional epitopes elicited by natural exposure and vaccination.
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Affiliation(s)
- Danton Ivanochko
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | | | - Karina Teelen
- Department of Medical Microbiology, Radboudumc, Nijmegen, the Netherlands
| | | | | | - Jocelyn Newton
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Anthony Semesi
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | | | | | - Jordache Ramjith
- Radboud Institute for Health Sciences, Department for Health Evidence, Biostatistics Section, Radboudumc, Nijmegen, the Netherlands
| | | | | | - Lucas Kraft
- AbCellera Biologics Inc., Vancouver, BC, Canada
| | | | - Shwu-Maan Lee
- PATH's Malaria Vaccine Initiative, Washington, DC 20001, USA
| | - Moses R Kamya
- Infectious Disease Research Collaboration, Kampala, Uganda
| | - Margaret E Feeney
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA; Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Prasanna Jagannathan
- Department of Microbiology and Immunology, Stanford University, Stanford, CA, USA
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | | | - C Richter King
- PATH's Malaria Vaccine Initiative, Washington, DC 20001, USA
| | | | - Teun Bousema
- Department of Medical Microbiology, Radboudumc, Nijmegen, the Netherlands.
| | - Matthijs M Jore
- Department of Medical Microbiology, Radboudumc, Nijmegen, the Netherlands.
| | - Jean-Philippe Julien
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada; Departments of Biochemistry and Immunology, University of Toronto, Toronto, ON, Canada.
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9
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Adeshina OO, Nyame S, Milner J, Milojevic A, Asante KP. Barriers and facilitators to nationwide implementation of the malaria vaccine in Ghana. Health Policy Plan 2023; 38:28-37. [PMID: 36083007 PMCID: PMC9825729 DOI: 10.1093/heapol/czac077] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 08/05/2022] [Accepted: 09/09/2022] [Indexed: 01/12/2023] Open
Abstract
Interventions such as antimalarial drugs, bed nets and insecticides have helped curb the burden of malaria in the past decade, yet malaria remains a leading cause of morbidity and mortality in children below the age of 5 years. In 2019, Ghana, Malawi and Kenya in sub-Saharan Africa (countries with moderate to high transmission areas of malaria and deaths) started piloting the RTS,S/AS01E malaria vaccine in selected regions. Using qualitative methods, this study examined the main factors (forces) that will influence or hinder the nationwide implementation of the malaria vaccine, if approved, in Ghana. We conducted in-depth interviews with 12 key individuals (national, research/academia and programme implementing partners) in the public health sector in Ghana from October 2018 to February 2019. Results were analysed using Kurt Lewin's force field analysis to understand how organizations interact with their external environment in the delivery of health policies such as the implementation of the malaria vaccine. We found that the disease burden of malaria deaths in Ghana, the efficacy of the vaccine, stakeholder involvement and evidence for the feasibility of vaccine delivery generated by the consortium of researchers (body of researchers) that can track the implementation were the driving forces to scale up the vaccine into a routine health system. On the other hand, the needed logistics, funding, administration of the four-dose vaccine and follow-up were identified as potential barriers. The most influential force collectively highlighted by the respondents was the disease burden, and the most influential barrier was the logistics of delivering the vaccine. Our findings provide decision makers with key barriers and facilitators to guide policy and decision-making for malaria control in Ghana and other similar settings in low- and middle-income countries.
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Affiliation(s)
- Omolola Oyinkan Adeshina
- Department of Public Health, Environments and Society, London School of Hygiene & Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK
| | - Solomon Nyame
- Kintampo Health Research Centre, Ghana Health Service, P.O. Box 200, Kintampo North Municipality, Ghana
| | - James Milner
- Department of Public Health, Environments and Society, London School of Hygiene & Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Ai Milojevic
- Department of Public Health, Environments and Society, London School of Hygiene & Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Kwaku Poku Asante
- Kintampo Health Research Centre, Ghana Health Service, P.O. Box 200, Kintampo North Municipality, Ghana
- Department of Disease Control, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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10
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Thompson HA, Hogan AB, Walker PGT, Winskill P, Zongo I, Sagara I, Tinto H, Ouedraogo JB, Dicko A, Chandramohan D, Greenwood B, Cairns M, Ghani AC. Seasonal use case for the RTS,S/AS01 malaria vaccine: a mathematical modelling study. Lancet Glob Health 2022; 10:e1782-e1792. [PMID: 36400084 DOI: 10.1016/s2214-109x(22)00416-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 08/03/2022] [Accepted: 09/15/2022] [Indexed: 11/17/2022]
Abstract
BACKGROUND A 2021 clinical trial of seasonal RTS,S/AS01E (RTS,S) vaccination showed that vaccination was non-inferior to seasonal malaria chemoprevention (SMC) in preventing clinical malaria. The combination of these two interventions provided significant additional protection against clinical and severe malaria outcomes. Projections of the effect of this novel approach to RTS,S vaccination in seasonal transmission settings for extended timeframes and across a range of epidemiological settings are needed to inform policy recommendations. METHODS We used a mathematical, individual-based model of malaria transmission that was fitted to data on the relationship between entomological inoculation rate and parasite prevalence, clinical disease, severe disease, and deaths from multiple sites across Africa. The model was validated with results from a phase 3b trial assessing the effect of SV-RTS,S in Mali and Burkina Faso. We developed three intervention efficacy models with varying degrees and durations of protection for our population-level modelling analysis to assess the potential effect of an RTS,S vaccination schedule based on age (doses were delivered to children aged 6 months, 7·5 months, and 9 months for the first three doses, and at 27 months of age for the fourth dose) or season (children aged 5-17 months at the time of first vaccination received the first three doses in the 3 months preceding the transmission season, with any subsequent doses up to five doses delivered annually) in seasonal transmission settings both in the absence and presence of SMC with sulfadoxine-pyrimethamine plus amodiaquine. This is modelled as a full therapeutic course delivered every month for four or five months of the peak in transmission season. Estimates of cases and deaths averted in a population of 100 000 children aged 0-5 years were calculated over a 15-year time period for a range of levels of malaria transmission intensity (Plasmodium falciparum parasite prevalence in children aged 2-10 years between 10% and 65%) and over two west Africa seasonality archetypes. FINDINGS Seasonally targeting RTS,S resulted in greater absolute reductions in malaria cases and deaths compared with an age-based strategy, averting an additional 14 000-47 000 cases per 100 000 children aged 5 years and younger over 15 years, dependent on seasonality and transmission intensity. We predicted that adding seasonally targeted RTS,S to SMC would reduce clinical incidence by up to an additional 42 000-67 000 cases per 100 000 children aged 5 years and younger over 15 years compared with SMC alone. Transmission season duration was a key determinant of intervention effect, with the advantage of adding RTS,S to SMC predicted to be smaller with shorter transmission seasons. INTERPRETATION RTS,S vaccination in seasonal settings could be a valuable additional tool to existing interventions, with seasonal delivery maximising the effect relative to an age-based approach. Decisions surrounding deployment strategies of RTS,S in such settings will need to consider the local and regional variations in seasonality, current rates of other interventions, and potential achievable RTS,S coverage. FUNDING UK Medical Research Council, UK Foreign Commonwealth & Development Office, The Wellcome Trust, and The Royal society.
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Affiliation(s)
- Hayley A Thompson
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London UK
| | - Alexandra B Hogan
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London UK; School of Population Health, University of New South Wales, Sydney, NSW, Australia
| | - Patrick G T Walker
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London UK
| | - Peter Winskill
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London UK
| | - Issaka Zongo
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Issaka Sagara
- Malaria Research and Training Center, University of Sciences, Technologies, and Techniques of Bamako, Bamako, Mali
| | - Halidou Tinto
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso; Institut National de Santé Publique - Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Jean-Bosco Ouedraogo
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso; Institut Sciences et Techniques, Bobo-Dioulasso, Burkina Faso
| | - Alassane Dicko
- Malaria Research and Training Center, University of Sciences, Technologies, and Techniques of Bamako, Bamako, Mali
| | - Daniel Chandramohan
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Brian Greenwood
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Matt Cairns
- International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London UK.
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11
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Yang T, Deng W, Liu Y, Deng J. Comparison of health-oriented cross-regional allocation strategies for the COVID-19 vaccine: a mathematical modelling study. Ann Med 2022; 54:941-952. [PMID: 35393922 PMCID: PMC9004521 DOI: 10.1080/07853890.2022.2060522] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
BACKGROUND Controlling the epidemic spread and establishing the immune barrier in a short time through accurate vaccine demand prediction and optimised vaccine allocation strategy are still urgent problems to be solved under the condition of frequent virus mutations. METHODS A cross-regional Susceptible-Exposed-Infected-Removed dynamic model was used for scenario simulation to systematically elaborate and compare the effects of different cross-regional vaccine allocation strategies on the future development of the epidemic in regions with different population sizes, prevention and control capabilities, and initial risk levels. Furthermore, the trajectory of the cross-regional vaccine allocation strategy, calculated using a particle swarm optimisation algorithm, was compared with the trajectories of other strategies. RESULTS By visualising the final effect of the particle swarm optimisation vaccine allocation strategy, this study revealed the important role of prevention and control (including the level of social distancing control, the speed of tracking and isolating exposed and infected individuals, and the initial frequency of mask-wearing) in determining the allocation of vaccine resources. Most importantly, it supported the idea of prioritising control in regions with a large population and low initial risk level, which broke the general view that high initial risk needs to be given priority and proposed that outbreak risk should be firstly considered instead. CONCLUSIONS This is the first study to use a particle swarm optimisation algorithm to study the cross-regional allocation of COVID-19 vaccines. These data provide a theoretical basis for countries and regions to develop more targeted and sustainable vaccination strategies.KEY MESSAGEThe innovative combination of particle swarm optimisation and cross-regional SEIR model to simulate the pandemic trajectory and predict the vaccine demand helped to speed up and stabilise the construction of the immune barrier, especially faced with new virus mutations.We proposed that priority should be given to regions where it is possible to prevent more infections rather than regions where it is at high initial risk, thus regional outbreak risk should be considered when making vaccine allocation decisions.An optimal health-oriented strategy for vaccine allocation in the COVID-19 pandemic is determined considering both pharmaceutical and non-pharmaceutical policy interventions, including speed of isolation, degree of social distancing control, and frequency of mask-wearing.
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Affiliation(s)
- Tianan Yang
- School of Management and Economics, Beijing Institute of Technology, Beijing, China.,Sustainable Development Research Institute for Economy and Society of Beijing, Beijing, China
| | - Wenhao Deng
- School of Management and Economics, Beijing Institute of Technology, Beijing, China.,Sustainable Development Research Institute for Economy and Society of Beijing, Beijing, China
| | - Yexin Liu
- School of Management and Economics, Beijing Institute of Technology, Beijing, China.,Sustainable Development Research Institute for Economy and Society of Beijing, Beijing, China
| | - Jianwei Deng
- School of Management and Economics, Beijing Institute of Technology, Beijing, China.,Sustainable Development Research Institute for Economy and Society of Beijing, Beijing, China
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12
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13
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Madewell ZJ, Whitney CG, Velaphi S, Mutevedzi P, Mahtab S, Madhi SA, Fritz A, Swaray-Deen A, Sesay T, Ogbuanu IU, Mannah MT, Xerinda EG, Sitoe A, Mandomando I, Bassat Q, Ajanovic S, Tapia MD, Sow SO, Mehta A, Kotloff KL, Keita AM, Tippett Barr BA, Onyango D, Oele E, Igunza KA, Agaya J, Akelo V, Scott JAG, Madrid L, Kelil YE, Dufera T, Assefa N, Gurley ES, El Arifeen S, Spotts Whitney EA, Seib K, Rees CA, Blau DM. Prioritizing Health Care Strategies to Reduce Childhood Mortality. JAMA Netw Open 2022; 5:e2237689. [PMID: 36269354 PMCID: PMC9587481 DOI: 10.1001/jamanetworkopen.2022.37689] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
IMPORTANCE Although child mortality trends have decreased worldwide, deaths among children younger than 5 years of age remain high and disproportionately circumscribed to sub-Saharan Africa and Southern Asia. Tailored and innovative approaches are needed to increase access, coverage, and quality of child health care services to reduce mortality, but an understanding of health system deficiencies that may have the greatest impact on mortality among children younger than 5 years is lacking. OBJECTIVE To investigate which health care and public health improvements could have prevented the most stillbirths and deaths in children younger than 5 years using data from the Child Health and Mortality Prevention Surveillance (CHAMPS) network. DESIGN, SETTING, AND PARTICIPANTS This cross-sectional study used longitudinal, population-based, and mortality surveillance data collected by CHAMPS to understand preventable causes of death. Overall, 3390 eligible deaths across all 7 CHAMPS sites (Bangladesh, Ethiopia, Kenya, Mali, Mozambique, Sierra Leone, and South Africa) between December 9, 2016, and December 31, 2021 (1190 stillbirths, 1340 neonatal deaths, 860 infant and child deaths), were included. Deaths were investigated using minimally invasive tissue sampling (MITS), a postmortem approach using biopsy needles for sampling key organs and fluids. MAIN OUTCOMES AND MEASURES For each death, an expert multidisciplinary panel reviewed case data to determine the plausible pathway and causes of death. If the death was deemed preventable, the panel identified which of 10 predetermined health system gaps could have prevented the death. The health system improvements that could have prevented the most deaths were evaluated for each age group: stillbirths, neonatal deaths (aged <28 days), and infant and child deaths (aged 1 month to <5 years). RESULTS Of 3390 deaths, 1505 (44.4%) were female and 1880 (55.5%) were male; sex was not recorded for 5 deaths. Of all deaths, 3045 (89.8%) occurred in a healthcare facility and 344 (11.9%) in the community. Overall, 2607 (76.9%) were deemed potentially preventable: 883 of 1190 stillbirths (74.2%), 1010 of 1340 neonatal deaths (75.4%), and 714 of 860 infant and child deaths (83.0%). Recommended measures to prevent deaths were improvements in antenatal and obstetric care (recommended for 588 of 1190 stillbirths [49.4%], 496 of 1340 neonatal deaths [37.0%]), clinical management and quality of care (stillbirths, 280 [23.5%]; neonates, 498 [37.2%]; infants and children, 393 of 860 [45.7%]), health-seeking behavior (infants and children, 237 [27.6%]), and health education (infants and children, 262 [30.5%]). CONCLUSIONS AND RELEVANCE In this cross-sectional study, interventions prioritizing antenatal, intrapartum, and postnatal care could have prevented the most deaths among children younger than 5 years because 75% of deaths among children younger than 5 were stillbirths and neonatal deaths. Measures to reduce mortality in this population should prioritize improving existing systems, such as better access to antenatal care, implementation of standardized clinical protocols, and public education campaigns.
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Affiliation(s)
- Zachary J. Madewell
- Center for Global Health, US Centers for Disease Control and Prevention, Atlanta, Georgia
| | | | - Sithembiso Velaphi
- Chris Hani Baragwanath Academic Hospital, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Portia Mutevedzi
- South African Medical Research Council Vaccines and Infectious Diseases Analytics Research Unit, University of the Witwatersrand, Johannesburg, South Africa
| | - Sana Mahtab
- Department of Obstetrics and Gynaecology, University of Ghana Medical School, Accra, Ghana
| | - Shabir A. Madhi
- South African Medical Research Council Vaccines and Infectious Diseases Analytics Research Unit, University of the Witwatersrand, Johannesburg, South Africa
| | - Ashleigh Fritz
- South African Medical Research Council Vaccines and Infectious Diseases Analytics Research Unit, University of the Witwatersrand, Johannesburg, South Africa
| | - Alim Swaray-Deen
- Department of Obstetrics and Gynaecology, University of Ghana Medical School, Accra, Ghana
| | - Tom Sesay
- Ministry of Health and Sanitation, Freetown, Sierra Leone
| | | | | | | | - Antonio Sitoe
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
| | - Inacio Mandomando
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
- Instituto Nacional de Saúde, Maputo, Mozambique
| | - Quique Bassat
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
- ISGlobal–Hospital Clínic, Unversitat de Barcelona, Barcelona, Spain
- Institutó Catalana de Recerca I Estudis Avançats, Barcelona, Spain
- Pediatrics Department, Hospital Sant Joan de Déu, Universitat de Barcelona, Esplugues, Barcelona, Spain
- Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública, Madrid, Spain
| | - Sara Ajanovic
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
- ISGlobal–Hospital Clínic, Unversitat de Barcelona, Barcelona, Spain
| | - Milagritos D. Tapia
- Department of Pediatrics and Department of Medicine, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore
| | - Samba O. Sow
- Centre pour le Développement des Vaccins, Ministère de la Santé, Bamako, Mali
| | - Ashka Mehta
- Department of Pediatrics and Department of Medicine, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore
| | - Karen L. Kotloff
- Department of Pediatrics and Department of Medicine, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore
| | - Adama M. Keita
- Centre pour le Développement des Vaccins, Ministère de la Santé, Bamako, Mali
| | | | | | | | | | - Janet Agaya
- Kenya Medical Research Institute-Center for Global Health Research, Kisumu, Kenya
| | - Victor Akelo
- Centers for Disease Control and Prevention–Kenya, Kisumu, Kenya
| | - J. Anthony G. Scott
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Lola Madrid
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
- College of Health and Medical Sciences, Haramaya University, Harar, Ethiopia
| | - Yunus-Edris Kelil
- College of Health and Medical Sciences, Haramaya University, Harar, Ethiopia
| | - Tadesse Dufera
- College of Health and Medical Sciences, Haramaya University, Harar, Ethiopia
| | - Nega Assefa
- College of Health and Medical Sciences, Haramaya University, Harar, Ethiopia
| | - Emily S. Gurley
- International Center for Diarrhoeal Diseases Research, Dhaka, Bangladesh
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Shams El Arifeen
- International Center for Diarrhoeal Diseases Research, Dhaka, Bangladesh
| | - Ellen A. Spotts Whitney
- International Association of National Public Health Institutes, Global Health Institute, Emory University, Atlanta, Georgia
| | - Katherine Seib
- International Association of National Public Health Institutes, Global Health Institute, Emory University, Atlanta, Georgia
| | - Chris A. Rees
- Division of Pediatric Emergency Medicine, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, Georgia
| | - Dianna M. Blau
- Center for Global Health, US Centers for Disease Control and Prevention, Atlanta, Georgia
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14
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Kanagat S, Boratne AV. Vaccine against malaria: A ground-breaking step towards elimination in India. J Vector Borne Dis 2022; 59:386-387. [PMID: 36751771 DOI: 10.4103/0972-9062.355961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Sadhvika Kanagat
- Department of Community Medicine, Mahatma Gandhi Medical College and Research Institute, Puducherry, India
| | - Abhijit Vinodrao Boratne
- Department of Community Medicine, Mahatma Gandhi Medical College and Research Institute, Puducherry, India
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15
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Oladipo HJ. Increasing challenges of malaria control in sub-Saharan Africa: Priorities for public health research and policymakers. Ann Med Surg (Lond) 2022; 81:104366. [PMID: 36046715 PMCID: PMC9421173 DOI: 10.1016/j.amsu.2022.104366] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 08/11/2022] [Indexed: 11/21/2022] Open
Abstract
The ever-increasing cases and mortality due to malaria remains one of the most important public health threats, especially in sub-Saharan Africa-where this burden is considerably high. In 2020, sub-Saharan Africa accounted for about 95% of all cases and 96% of all malaria deaths with about 80% of these deaths reported in children under the age of 5. This review, adopting a public health focus, aimed to understand the challenges of malaria control in sub-Saharan Africa despite ongoing public health interventions. Our review highlights two important findings. First, the increasing resistance of malaria parasites to artemisinin-based combination therapy (ACT) and its partner drugs coupled with increased vector resistance to pyrethroids and insecticides is reversing the progress of public health interventions in keeping malaria under control. Second, the wanning for the efficacy of the WHO-approved vaccine i.e. RTS,S from 60 to 70% following 18 months of observation, and its short-term availability remains an impediment to achieving the WHO target of producing malaria vaccines with more than 75% efficacy by 2030. Our findings underline the need to reassess research priorities with a focus on vaccine production in sub-Saharan Africa. Furthermore, African governments and policymakers must be committed to invest both the political and financial capital in vaccine production and distribution.
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Abstract
"The Primate Malarias" book has been a uniquely important resource for multiple generations of scientists, since its debut in 1971, and remains pertinent to the present day. Indeed, nonhuman primates (NHPs) have been instrumental for major breakthroughs in basic and pre-clinical research on malaria for over 50 years. Research involving NHPs have provided critical insights and data that have been essential for malaria research on many parasite species, drugs, vaccines, pathogenesis, and transmission, leading to improved clinical care and advancing research goals for malaria control, elimination, and eradication. Whilst most malaria scientists over the decades have been studying Plasmodium falciparum, with NHP infections, in clinical studies with humans, or using in vitro culture or rodent model systems, others have been dedicated to advancing research on Plasmodium vivax, as well as on phylogenetically related simian species, including Plasmodium cynomolgi, Plasmodium coatneyi, and Plasmodium knowlesi. In-depth study of these four phylogenetically related species over the years has spawned the design of NHP longitudinal infection strategies for gathering information about ongoing infections, which can be related to human infections. These Plasmodium-NHP infection model systems are reviewed here, with emphasis on modern systems biological approaches to studying longitudinal infections, pathogenesis, immunity, and vaccines. Recent discoveries capitalizing on NHP longitudinal infections include an advanced understanding of chronic infections, relapses, anaemia, and immune memory. With quickly emerging new technological advances, more in-depth research and mechanistic discoveries can be anticipated on these and additional critical topics, including hypnozoite biology, antigenic variation, gametocyte transmission, bone marrow dysfunction, and loss of uninfected RBCs. New strategies and insights published by the Malaria Host-Pathogen Interaction Center (MaHPIC) are recapped here along with a vision that stresses the importance of educating future experts well trained in utilizing NHP infection model systems for the pursuit of innovative, effective interventions against malaria.
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Affiliation(s)
- Mary R Galinski
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, USA.
- Emory Vaccine Center, Emory University, Atlanta, GA, USA.
- Emory National Primate Research Center (Yerkes National Primate Research Center), Emory University, Atlanta, GA, USA.
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17
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Efficacy, T cell activation and antibody responses in accelerated Plasmodium falciparum sporozoite chemoprophylaxis vaccine regimens. NPJ Vaccines 2022; 7:59. [PMID: 35641527 PMCID: PMC9156686 DOI: 10.1038/s41541-022-00473-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 03/18/2022] [Indexed: 11/08/2022] Open
Abstract
Repeated direct venous inoculation of Plasmodium falciparum sporozoites (PfSPZ) together with antimalarial chemoprophylaxis (PfSPZ-CVac) is the most potent way to induce sterile immunity against P. falciparum infection in malaria-naive volunteers. However, established schedules are complex and long. Here, we tested two accelerated three-dose schedules (28- and 10-day regimen) assessing efficacy by controlled human malaria infection (CHMI) against placebo, comparing vaccine-specific T cell and antibody responses by antigen-reactive T cell enrichment (ARTE) and protein microarray, respectively. Both regimens were similarly efficacious (67 and 63% vaccine efficacy) but different in the induction of vaccine-specific T cells and antibodies. The 10-day regimen resulted in higher numbers of antigen-specific CD4+ effector memory pro-inflammatory T cells and a broader antibody response compared with the 28-day regimen. Usually in nature, P. falciparum liver stage lasts about 6.5 days. The short vaccination-interval of the 10-day regimen prolongs the time of continuous exposure to liver-stage parasites, which may explain the stronger response. Besides dose and number of vaccinations, duration of liver-stage exposure is a factor to optimize PfSPZ-CVac immunogenicity.
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18
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Jagannathan P, Kakuru A. Malaria in 2022: Increasing challenges, cautious optimism. Nat Commun 2022; 13:2678. [PMID: 35562368 PMCID: PMC9106727 DOI: 10.1038/s41467-022-30133-w] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/12/2022] [Indexed: 01/29/2023] Open
Affiliation(s)
- Prasanna Jagannathan
- grid.168010.e0000000419368956Department of Medicine, Stanford University, Stanford, CA United States ,grid.168010.e0000000419368956Department of Microbiology and Immunology, Stanford University, Stanford, CA United States
| | - Abel Kakuru
- grid.463352.50000 0004 8340 3103Infectious Diseases Research Collaboration, Kampala, Uganda
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19
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Malaria research supported with open access data. Data Brief 2022; 41:108009. [PMID: 35252506 PMCID: PMC8888349 DOI: 10.1016/j.dib.2022.108009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Mondal A, Vásquez VN, Marshall JM. Target Product Profiles for Mosquito Gene Drives: Incorporating Insights From Mathematical Models. FRONTIERS IN TROPICAL DISEASES 2022. [DOI: 10.3389/fitd.2022.828876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mosquito-borne diseases such as malaria continue to pose a major global health burden, and the impact of currently-available interventions is stagnating. Consequently, there is interest in novel tools to control these diseases, including gene drive-modified mosquitoes. As these tools continue to be refined, decisions on whether to implement them in the field depend on their alignment with target product profiles (TPPs) that define product characteristics required to achieve desired entomological and epidemiological outcomes. TPPs are increasingly being used for malaria and vector control interventions, such as attractive targeted sugar baits and long-acting injectable drugs, as they progress through the development pipeline. For mosquito gene drive products, reliable predictions from mathematical models are an essential part of these analyses, as field releases could potentially be irreversible. Here, we review the prior use of mathematical models in developing TPPs for malaria and vector control tools and discuss lessons from these analyses that may apply to mosquito gene drives. We recommend that, as gene drive technology gets closer to field release, discussions regarding target outcomes engage a wide range of stakeholders and account for settings of interest and vector species present. Given the relatively large number of parameters that describe gene drive products, machine learning approaches may be useful to explore parameter space, and an emphasis on conservative fitness estimates is advisable, given the difficulty of accurately measuring these parameters prior to field studies. Modeling may also help to inform the risk, remediation and cost dimensions of mosquito gene drive TPPs.
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Tabong PTN, Opoku Mensah K, Asampong E. Preparation for COVID-19 vaccines rollout: Interventions to increase trust, acceptability, and uptake in West African countries. Int J Health Plann Manage 2022; 37:1221-1228. [PMID: 35104374 PMCID: PMC9015502 DOI: 10.1002/hpm.3426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 09/13/2021] [Accepted: 01/18/2022] [Indexed: 11/10/2022] Open
Abstract
Introduction The approval of COVID‐19 vaccines for use has come as a relief to West Africa and world. However, concerns raised about the vaccines in America and Europe have created anxiety among some citizens in Africa. These concerns are likely to affect the acceptance, and uptake of the COVID‐19 vaccines in West Africa. Methods Guided by the principles of effective community engagement, this research reviewed typical case studies of past vaccination exercises to document concerns, challenges and lessons learnt. These were then used to propose pre‐immunisation interventions in West Africa to increase the COVID‐19 vaccines acceptance and uptake. Results Concerns about safety can undermine the rollout of the COVID‐19 vaccines. These concerns can be addressed through effective community engagement. Community leaderships could be engaged through courtesy calls, workshops and durbars to sensitise them on immunisation. Engaging the scientific community can help build trust and reduce concerns about vaccine safety. In vaccines rollout, managing misinformation is important and the media can play a critical role in addressing these in their reportage. In addition, social media is an effective monitoring tool for vaccine‐related misinformation. Conclusion The analysis underscores the need for more community engagement before the importation and deployment of COVID‐19 vaccines in West Africa. Experiences from community responses to previous vaccination exercises for emerging and remerging infectious diseases should inform the current efforts and enhance the process to achieve high uptake and reduce vaccine hesitancy. Concerns about safety have often undermined the rollout of new vaccines High COVID‐19 vaccine hesitancy has been reported across the world Effective local community engagement strategies can reduce vaccine hesitancy Social media is an effective monitoring tool for vaccine‐related misinformation
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Affiliation(s)
- Philip Teg-Nefaah Tabong
- Department of Social and Behavioural Sciences, School of Public Health, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Kwabena Opoku Mensah
- Department of Social and Behavioural Sciences, School of Public Health, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Emmanuel Asampong
- Department of Social and Behavioural Sciences, School of Public Health, College of Health Sciences, University of Ghana, Accra, Ghana
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22
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D'Souza J, Nderitu D. Ethical considerations for introducing RTS,S/AS01 in countries with moderate to high Plasmodium falciparum malaria transmission. Lancet Glob Health 2021; 9:e1642-e1643. [PMID: 34798015 DOI: 10.1016/s2214-109x(21)00498-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 11/28/2022]
Affiliation(s)
- Jeff D'Souza
- Institute for Better Health, Trillium Health Partners, Mississauga, ON L5B 1B8, Canada.
| | - David Nderitu
- Department of Philosophy, History and Religious Studies, Egerton University, Njoro, Kenya
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Galactionova K, Smith TA, Penny MA. Insights from modelling malaria vaccines for policy decisions: the focus on RTS,S. Malar J 2021; 20:439. [PMID: 34794430 PMCID: PMC8600337 DOI: 10.1186/s12936-021-03973-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 11/04/2021] [Indexed: 11/17/2022] Open
Abstract
Mathematical models are increasingly used to inform decisions throughout product development pathways from pre-clinical studies to country implementation of novel health interventions. This review illustrates the utility of simulation approaches by reviewing the literature on malaria vaccine modelling, with a focus on its link to the development of policy guidance for the first licensed product, RTS,S/AS01. The main contributions of modelling studies have been in inferring the mechanism of action and efficacy profile of RTS,S; to predicting the public health impact; and economic modelling mainly comprising cost-effectiveness analysis. The value of both product-specific and generic modelling of vaccines is highlighted.
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Affiliation(s)
- Katya Galactionova
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland.,University of Basel, 4001, Basel, Switzerland.,European Center of Pharmaceutical Medicine, Brombacherstrasse 5, 4057, Basel, Switzerland
| | - Thomas A Smith
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland. .,University of Basel, 4001, Basel, Switzerland.
| | - Melissa A Penny
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland.,University of Basel, 4001, Basel, Switzerland
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Maxmen A. Scientists hail historic malaria vaccine approval - but point to challenges ahead. Nature 2021:10.1038/d41586-021-02755-5. [PMID: 34625728 DOI: 10.1038/d41586-021-02755-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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